In recent years, energy harvesting (environmental power generation) devices such as a wireless sensor or a remote control switch have attracted attention due to achievement of low power consumption in an electronic circuit or a wireless technique. An energy harvesting device obtains electrical energy from the ambient environment and thus operates without wiring or batteries being replaced. As an energy harvesting device, for example, a low illuminance dye-sensitized solar battery for energy harvesting which is expected to be able to be used in indoor light from a fluorescent lamp or an LED lamp is currently being developed.
Patent Document 1 discloses a power generation system which obtains an appropriate power generation amount required by a solar battery on the basis of the required power, and adjusts a power generation amount of the solar battery according to the obtained power generation amount.
Patent Document 2 discloses a power source device provided with a plurality of power storage portions with different capacities in order to effectively charge the power storage portions with power generated by a solar battery.
Patent Document 3 discloses a power source device provided with a switch circuit which switches between connection to a light power generation portion of a capacitor and connection to a battery of the capacitor.